Various tumor and cancer related diseases afflict man and animals. The term “tumor” refers to abnormal masses of new tissue growth which is discordant with the economy of the tissue of origin or of the host's body as a whole. Tumors inflict mammals and man with a variety of disorders and conditions, including various forms of cancer. The seriousness of cancer is well known, e.g. cancer is second only to heart and vascular diseases as a cause of death in man. Tumors are common in a variety of mammals, and the prevention and control of the growth and regression of tumors in mammals is important to man.
Considerable research and resources have been devoted to oncology and antitumor measures, including chemotherapy. While certain methods and chemical compositions have been developed which aid in inhibiting, remitting, or controlling the growth of tumors and other forms of cancer, further antitumor methods and chemical compositions are needed.
It has been found that some natural products and organisms are potential sources for chemical molecules having useful biological activities. For example, the diterpene commonly known as taxol, isolated from several species of yew trees, is a mitotic spindle poison that stabilizes microtubules and inhibits their depolymerization to free tubulin (Fuchs, D. A., R. K. Johnson [1978] Cancer Treat. Rep. 62:1219–1222; Schiff, P. B., J. Fant, S. B. Horwitz [1979] Nature (London) 22:665–667). Taxol is also known to have antitumor activity and has undergone a number of clinical trials which have shown it to be effective in the treatment of a wide range of cancers (Rowinski, E. K. R. C. Donehower [1995] N. Engl. J. Med. 332:1004–1014). See also, e.g., U.S. Pat. Nos. 5,157,049; 4,960,790; and 4,206,221.
Marine life has been the source for the discovery of compounds having varied biological activities. Some of the United States patents which have issued for such inventions are as follows: U.S. Pat. No. 4,548,814 for didemnins, having antiviral activity, were isolated from a marine tunicate; U.S. Pat. No. 4,729,996 discloses compounds, having antitumor properties, that were isolated from marine sponges Teichaxinella morchella and Ptilocaulis walpersi; U.S. Pat. No. 4,808,590 discloses compounds, having antiviral, antitumor, and antifungal properties, isolated from the marine sponge Theonella sp.; and U.S. Pat. No. 4,737,510 discloses compounds, having antiviral and antibacterial properties, isolated from the Caribbean sponge Agelas coniferin. 
A number of publications disclose organic compounds derived from marine sponges including Scheuer, P. J. (ed.) Marine Natural Products, Chemical and Biological Perspectives, Academic Press, New York, 1978–1983, Vol. I–V; Uemura, D., K. Takahashi, T. Yamamoto, C. Katayama, J. Tanaka, Y. Okumura, Y. Hirata (1985) J. Am. Chem. Soc. 107:4796–4798; Minale, L. et al. (1976) Fortschr. Chem. org. Naturst. 33:1–72; Faulkner, D. J. (1998) Natural Products Reports 15:113–158; and Gunasekera, S. P., M. Gunasekera, R. E. Longley and G. K. Schulte (1990) “Discodermolide: A new bioactive polyhydroxy lactone from the marine sponge Discodermia dissoluta” J. Org. Chem., 55:4912–4915 [correction (1991) J. Org. Chem. 56:1346]. U.S. Pat. No. 4,808,590 discloses compounds, having antiviral, antitumor, and antifungal properties, isolated from the marine sponge Theonella sp. (International Patent Application No. WO 9824429; Kowalski, R. J., P. Giannakakou, S. P. Gunasekera et al. (1997) Mol. Pharmacol 52:613–622; ter Haar, E., R. J. Kowalski, E. Hamel et al. (1996) Biochemistry 35:243–250; Stafford, J. A. and M. M. Mehrotra (1995) Chemtract: Org. Chem. 8:41–47; and U.S. Pat. No. 5,789,605.